Rotten trunk on banana tree
I have a 6 foot banana tree that was first planted in my North Carolina back yard last year and it did beautifully. Dug it up and overwintered inside and it continued to grow and flourish. This past April, I planted it back outside in same spot as last year however now it is struggling with growth (has only produced 1 new leaf in 2 months)and even more disturbing is the obvious rotting at the top of the trunk. It seemed that perhaps water was being trapped in the upper layers of the trunk where it peels back some so I peeled it back and removed rotten edges and followed a recommendation to water it with a solution of Epsom salt. Rot did not re-appear for a while but is now back. The leaves, though few, are healty and normal looking. The NC soil that it is planted in contains a lot of clay, though I did ammend it a bit when planting with manure and top soil. I'm not sure if tree is experiencing a drainage issue or if this is a disease. Any advice?